An industrial process transmitter generally includes a transducer or sensor that responds to a measured variable with a sensing element that converts the variable to a standardized transmission signal, e.g., an electrical or optical signal that is a function of the measured value. Industrial process pressure transmitters are used to measure pressure within industrial processes such as slurries, liquids, vapors and gases in chemical, pulp, petroleum, gas, pharmaceutical, food, and other fluid processing plants. Industrial process transmitters are often placed near the process fluids, or in field applications. Often, these field applications are subject to harsh and varying environmental conditions that provide challenges for designers of such transmitters.
Industrial process pressure transmitters are typically connected to the process to be monitored by an isolation manifold. An isolation manifold typically includes one or more valves that can be closed to isolate the process fluid pressure transmitter from the process for service (e.g., calibration) or removal of the process fluid pressure transmitter. Isolation manifolds may also include a bleed port that can be used to relieve pressure in the manifold before servicing or removal. In some instances, a bleed port will include a bleed screw or valve that is operable to open or seal the bleed port. Isolation manifolds including an isolation valve as well as a bleed port are also referred to as block and bleed manifolds.